Hey everyone, i was recommended to do a radiator flush, it has 120,000 miles, and i also dont know if its something i can do myself i am not familiar with cadillac's or Narthstars but am really wanting to learn

maeng9981

03-06-11, 02:44 AM

Forget about flushing, drain & refill will be enough. It is very easy to do. The cooling system of Northstar engines is self-purging.

1. Open the plastic drain plug (19mm) under the radiator and the coolant will start flowing out of the radiator.
2. Adding a GM sealant tab is your choice.
3. Put the drain plug back in (hand tight) and fill 50/50 mix of Dex-Cool to the half line of the tank.
4. Close the coolant tank and start the engine.
5. Run the engine to about 2,500-3,000rpm several times.
6. Turn off the engine before it hits operating temperature and let it cool down; carefully check the coolant level.
6.1. If dropped(most likely), fill it back to the half line of the surge tank.
7. Either repeat steps 6-6.1 or take the car for test drive, run the engine in various RPMs and come back; let it cool down.
8. Carefully check for the coolant level change and fill it back to the half mark if necessary.
9. Repeat steps 7-8 until there is no coolant level change.

Note that opening the cooling system with hot coolant not only will give you false reading but also could possibly burn you. Also it is a very good time to check purge line for coolant flow; it should flow coolant all the time when the engine is running.

Nash-tasic

03-06-11, 02:47 AM

oh nice. thank you that does sound easy! how often is that recommended to do

Submariner409

03-06-11, 11:34 AM

oh nice. thank you that does sound easy! how often is that recommended to do

Using a 50/50 mix of DEX-COOL and distilled water I would do it every third spring - 3 years. GM says 5 years.

Ranger

03-06-11, 03:06 PM

It will be much easier and less of a mess if you drop the plastic splash shield under the radiator before doing the job.

jrb03deville

09-22-12, 01:28 PM

Hi

I want to flush mine to but what about the rest of the system, is there a recommendation for flushing and rinsing the whole system?

Ranger

09-22-12, 02:38 PM

It is all but impossible to get all the coolant out. The only way is to drain it and refill with water. Run it and drain it again until the mix gets very thin, but then you have the problem of getting it back to a 50/50 mix since you now will have almost straight water remaining in the system. Best to just drain what you can and refill with a 50/50 mix.

Submariner409

09-22-12, 02:40 PM

Discussions: Cadillac Tech Tips.

Do all the recommended drain/shop vac/refill/bleed/refill work and make sure the purge line and hollow bolt/nipple flow a steady stream of coolant. Coolant level is halfway up in the reservoir, cold. Never adjust coolant levels with a hot engine.

Unless you do some really creative work with a shop vac and break into the heater circuit you'll NEVER get all the old coolant out - a simple drain and refill every 3 years is more than enough to maintain the coolant additive packages at safe levels.

The best, peace-of-mind "flush" is to take advantage of a GM dealer "Fall Special" and have the coolant, brake fluid, transmission fluid and P/S fluid exchanged. You have an invoice, a service record, and some sort of warranty on the work.

Bone dry, your system holds about 12.5 quarts of 50/50 DEX-COOL. 2 gallons of 100% DEX-COOL, 2 gallons of distilled water from the grocery store. Find a 2 quart pitcher. Pour 1/2 jug of distilled water in the pitcher. Fill the water jug with DEX-COOL. Pour the pitcher of water into the DEX-COOL jug. 2 gallons of 50/50 mix and a clean pitcher. Repeat.

If the system had no nuisance weeps before the coolant exchange, don't use any sealants or tablets. (Post #2)

............... hello, Ranger !!!!

Ranger

09-22-12, 02:56 PM

:wave:

Submariner409

09-22-12, 03:55 PM

All this fall coolant flush stuff motivated me to exchange another 2 quarts of coolant about 20 minutes ago - this is after the earlier farm road run to just over 125. Here's what coolant should look like when you drain it out. (I do this drill every 3 months - every 3 months, so in effect I change 2 gallons of coolant every year.) Siphon out 2 quarts, refill with same amount of 50/50.

bm85

04-28-13, 11:50 AM

ok I cant believe I just read all that, people have advised you to do a drain and fill of your coolant. That is not sufficient enough. You need to go to MR. Lube or penzoil or wherever and pay the 99.99 and have a coolant flush. You cant do a proper coolant flush yourself unless by rigging some sort of home made shop vac thing. When they do a coolant flush they use a special machine that sucks all the old coolant out from your blower, block, engine, rad, lines etc, and replace it with new coolant, the amount of money and time your going to spend on buying coolant, and the labour your going to put in, and the possibility of burning your self and the mess, your better off paying the 100. Its recommended to do it every 50k or so, varies by vehicle.

Ranger

04-28-13, 12:26 PM

ok I cant believe I just read all that, people have advised you to do a drain and fill of your coolant. That is not sufficient enough.
Do tell. Please educate us.

Submariner409

04-28-13, 04:05 PM

This is gonna be good ........... I wonder if this guy is a front man for the anti-Right To Repair greenies.

On one hand, I believe that a (trusted) GM dealership fluids exchange package is a recommended interval worthwhile investment in automobile maintenance; On the other hand - I would NEVER let my car within 100 yards of an Oil Doodle - to even vacuum the carpets.

maeng9981

04-29-13, 05:27 AM

I would NEVER let my car within 100 yards of an Oil Doodle - to even vacuum the carpets.

:yeah: I once let them replace the battery on our van since it was a free service that came with battery purchase, and they managed to mess up the one and only thing that needs to be removed to replace the battery. They put the tower to tower brace wrong and bent it to make it fit in the wrong place.

I bet they'll use power tools on the drain plug and break it. Or mix orange with green. They'll probably suggest you to use stop leak also. Same "mechanics" who say all Northstars have blown head gaskets.

rodnok01

04-29-13, 09:05 AM

Do not go to quicky lubes for AF flushes. Last time my wife did they used 50/50 in the machine instead of pure. Of course they didn't check it. When I did it was good to about 10F. When they asked why I checked I told them I knew they would dork it up, they also left the rad drain plug loose. I77 in mtns 2am rest area I noticed AF leaking, the plug had 1/2 a thread before it fell out. Good stuff.

Submariner409

04-29-13, 11:47 AM

You need to read the boil/freeze data for 50/50 ethylene glycol based coolants - it's on the back of any coolant jug.

50/50 mix is the recommended strength by every car maker on earth since they stopped using alcohol-based coolants in the 40's.

Like it or not, 100% coolant boils and freezes earlier than the 50/50 mix - and, for high temperature operation, GM's highest recommended concentration is 70/30.

hi
Where is minimum level In coolant tank?After when I changed coolant and fill up to max always come down.That normal?Or I losing coolant?Two times happen when engine idling and cut off and when engine idling and seat in car I feel little little shake.RPM OK but slighty feel.???

Submariner409

05-28-13, 05:02 PM

Read the fill legend molded into the reservoir top and side.

Filled to or close to the top, as the coolant normally expands quite a bit as it warms up it blows out the overflow hose. Normal level - when cold - is about halfway up in the reservoir. You never check or adjust coolant level with the engine hot - only when less than lukewarm.

If the engine stalls when idling, get any diagnostic trouble codes from the car's built-in code reader/scanner. Use the proper section and links in the sticky post just above this - "How to pull codes". Practice, write down all found codes and whether each is Current or History and return to the sticky to open the link of code definitions. Decipher all your P,B,C, and U codes, write it all down, and post it all here.

( There are two sticky posts in the Engines; Northstar Performance forum that address cooling system operation. Also, a discussion way up ^^^ in the Cadillac Technical Archive - black bar)

gino9

05-28-13, 05:53 PM

Ok,I'v found wet place under reservior tank,so I think I put too much coolant.When engine cold I add coolant for max level.After few days I losing 200ml.So is ok?

Ranger

05-29-13, 12:29 PM

After a coolant change you may have to top it off a few times as it purges air out of the system. That's normal.

If you are filling it to the 1/2 tank level (proper full level) and have a "wet place under reservoir tank", then you have a leak. Probably a cracked tank (not uncommon). That WILL NOT cause a stall.

As for minimum level (when the CHECK COOLANT message appears) that is somewhere around 1/4.

gino9

05-29-13, 03:56 PM

today I seen,when engine hot slowly come out on reservoir tank cap.So not sure he reduce because too much or I'v change cap?